Pests such as insects and acarids cause tremendous global economic losses by reducing crop yields and lowering crop quality. Arylpyrrole compounds are useful for the control of insect and acarid pests. However, it has been found that arylpyrrole particles present in suspension concentrate may not maintain a stable particle size. In particular, it has been found that certain arylpyrrole particles grow to an unacceptable size during storage.
Certain pesticidal arylpyrrole compounds and methods for their preparation and use are described in U.S. Pat. Nos. 5,010,098 and 5,233,051; and Canadian Patent Application Number 2,076,937. Chlorfenapyr (4-bromo-2-(p-chlorophenyl)-1-(ethoxymethyl)-5-(trifluoromethyl)pyrrole-3-carbonitrile) was the first arylpyrrole pesticide to be commercialized. Chlorfenapyr and methods for its preparation and use are described in U.S. Pat. No. 5,010,098.
Suspension concentrate compositions comprising arylpyrrole particles are disclosed in U.S. Pat. No. 5,496,845. However, it has been found that the particle size stability of the arylpyrrole compounds in the reference compositions is variable. Commonly, arylpyrrole particles known in the art increase in size during storage, i.e., an initial number of relatively small particles becomes a smaller number of larger particles. It is desirable to have particles whose sizes are predictably stable over time, to avoid undesired variations in the characteristics of formulations containing these particles.
The present invention provides stable arylpyrrole particles wherein more than about 20% of the arylpyrrole is in a stable crystalline form thereof.
The present invention further provides a process for the preparation of stable arylpyrrole particles which process comprises:
a) providing a first mixture comprising arylpyrrole particles, a dispersing agent and water;
b) keeping the first mixture in a temperature range of about 25xc2x0 C. to 80xc2x0 C. to obtain an aged mixture; and
c) milling, if necessary, the aged mixture to obtain stabilized arylpyrrole particles.
The present invention also provides stable arylpyrrole particles prepared by the process of this invention, and suspension concentrate compositions comprising arylpyrrole particles of this invention.
It is, therefore, an object of the present invention to provide a process for stabilizing arylpyrrole particles.
It is another object of this invention to provide stable arylpyrrole particles.
It is a further object of this invention to provide suspension concentrate compositions which comprise stable arylpyrrole particles.
These and other objects and advantages of the present invention will become more apparent from the detailed description thereof set forth below, and from the appended claims.